U.S. patent number 9,909,545 [Application Number 15/219,617] was granted by the patent office on 2018-03-06 for outboard motor with sound enhancement device and method for modifying sounds produced by air intake system of an outboard motor.
This patent grant is currently assigned to Brunswick Corporation. The grantee listed for this patent is Brunswick Corporation. Invention is credited to Jeffrey J. Broman, Jeffrey C. Etapa, Brian J. Fregonese, Wayne M. Jaszewski, Andrew S. Waisanen.
United States Patent |
9,909,545 |
Waisanen , et al. |
March 6, 2018 |
Outboard motor with sound enhancement device and method for
modifying sounds produced by air intake system of an outboard
motor
Abstract
An outboard motor includes an internal combustion engine
powering the outboard motor and a cowl covering the engine and
having a vent allowing air under the cowl. A throttle body meters
flow of the air into the engine and an intake structure downstream
of the throttle body delivers the metered airflow to one or more
combustion chambers in a cylinder block of the engine. A sound
enhancement assembly in acoustic communication with the intake
structure collects sounds emitted by the engine. The sound
enhancement assembly is configured to amplify a subset of the
collected sounds that have frequencies within a desired frequency
range. A method for modifying sounds produced by an air intake
system of an internal combustion engine powering an outboard motor
is also disclosed. The method includes positioning a sound
enhancement assembly in acoustic communication with an air intake
passageway located downstream of the engine's throttle body.
Inventors: |
Waisanen; Andrew S. (Fond du
Lac, WI), Etapa; Jeffrey C. (Elkhart Lake, WI),
Jaszewski; Wayne M. (Jackson, WI), Broman; Jeffrey J.
(Slinger, WI), Fregonese; Brian J. (Fond du Lac, WI) |
Applicant: |
Name |
City |
State |
Country |
Type |
Brunswick Corporation |
Mettawa |
IL |
US |
|
|
Assignee: |
Brunswick Corporation (Mettawa,
IL)
|
Family
ID: |
61257165 |
Appl.
No.: |
15/219,617 |
Filed: |
July 26, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02B
61/045 (20130101); F02M 35/104 (20130101); F02M
35/10242 (20130101); B63H 20/32 (20130101) |
Current International
Class: |
F02M
35/12 (20060101); F02M 35/10 (20060101); B63H
20/00 (20060101); B63H 20/32 (20060101); F02M
35/104 (20060101); F02B 61/04 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
KC. Colwell, Faking It: Engine-Sound Enhancement Explained, Car and
Driver Website, Apr. 2012, available at
http://www.caranddriver.com/features/faking-it-engine-sound-enhancement-e-
xplained-tech-dept, 7 pages. cited by applicant .
Waisanen et al., Outboard Motor With Sound Enhancement Device and
Method for Modifying Sounds Produced by Air Intake System of an
Outboard Motor, Unpublished U.S. Appl. No. 15/091,007, filed Apr.
5, 2016. cited by applicant.
|
Primary Examiner: Polay; Andrew
Attorney, Agent or Firm: Andrus Intellectual Property Law,
LLP
Claims
What is claimed is:
1. An outboard motor comprising: an internal combustion engine
powering the outboard motor; a cowl covering the engine and having
a vent allowing air under the cowl; a throttle body metering flow
of the air into the engine; an intake structure downstream of the
throttle body that delivers the metered airflow to one or more
combustion chambers in a cylinder block of the engine; and a sound
enhancement assembly including an assembly housing, the sound
enhancement assembly being in acoustic communication with the
intake structure downstream of the throttle body and collecting
sounds emitted by the engine; wherein the sound enhancement
assembly includes a sound enhancement device located within the
assembly housing that is tuned to amplify a subset of the collected
sounds that have frequencies within a desired frequency range.
2. The outboard motor of claim 1, wherein the sound enhancement
assembly includes an inlet pipe coupled to the intake structure
that collects the sounds emitted by the engine and directs the
collected sounds into the assembly housing.
3. The outboard motor of claim 2, wherein the inlet pipe is coupled
to the intake structure upstream of a cylinder head attached to the
cylinder block of the engine.
4. The outboard motor of claim 2, wherein the sound enhancement
assembly includes an outlet pipe having an upstream end coupled to
the assembly housing downstream of the sound enhancement device,
wherein the outlet pipe transmits the amplified subset of the
collected sounds to an area outside the cowl.
5. The outboard motor of claim 4, wherein the sound enhancement
assembly includes an acoustically transparent shield positioned
above the inlet pipe upstream of the sound enhancement device that
protects the sound enhancement device from particulates in the
intake structure.
6. The outboard motor of claim 4, wherein a downstream end of the
outlet pipe is coupled to a lower portion of the cowl.
7. The outboard motor of claim 4, wherein the intake structure
defines a first passageway that is separate and distinct from a
second passageway defined by the outlet pipe.
8. The outboard motor of claim 4, wherein the assembly housing
comprises a first mounting flange that is integral with the intake
structure and a second mounting flange that is integral with the
upstream end of the outlet pipe, the first and second mounting
flanges being connected to one another in an airtight manner.
9. The outboard motor of claim 2, wherein the sound enhancement
device is a membrane, and further comprising a tensioner disk
clamped within the assembly housing and stretching the membrane to
maintain a given tension of the membrane.
10. The outboard motor of claim 9, further comprising at least one
travel guard disk located in the assembly housing on at least one
of an upstream side and a downstream side of the membrane that
prevents the membrane from distending by more than a predetermined
distance in response to a pressure pulse.
11. The outboard motor of claim 3, wherein the intake structure
comprises a plenum downstream of the throttle body and one or more
intake runners extending from the plenum to the one or more
combustion chambers of the engine, and wherein the inlet pipe is
coupled to the plenum.
12. A method for modifying sounds produced by an air intake system
of an internal combustion engine powering an outboard motor, the
method comprising: positioning a sound enhancement assembly
including an assembly housing in acoustic communication with an air
intake passageway located downstream of a throttle body of the
engine; providing the acoustic communication downstream of the
throttle body; tuning a sound enhancement device of the sound
enhancement assembly so that the sound enhancement device amplifies
a subset of sounds emitted by the engine that have frequencies
within a desired frequency range; transmitting the amplified subset
of sounds as sound pressure pulses through a sound passageway of
the sound enhancement assembly to an area outside a cowl covering
the engine; and preventing fluid communication between the air
intake passageway and the sound passageway by providing a
fluid-tight seal between the air intake passageway and the sound
passageway.
13. The method of claim 12, further comprising collecting sounds
emitted by the engine with an inlet pipe of the sound enhancement
assembly, the inlet pipe being coupled to the air intake passageway
so as to direct the collected sounds into the assembly housing.
14. The method of claim 13, wherein the sound enhancement device
comprises a flexible membrane, and further comprising placing the
membrane within the assembly housing and maintaining a given
tension on the membrane by stretching the membrane with a tensioner
disk.
15. The method of claim 13, further comprising providing at least
one travel guard disk in the assembly housing that prevents the
sound enhancement device from distending by more than a
predetermined distance in response to a pressure pulse.
16. The method of claim 15, further comprising providing a first
travel guard disk on an upstream side of the sound enhancement
device and a second travel guard disk on a downstream side of the
sound enhancement device.
17. The method of claim 13, further comprising providing a shield
upstream of the sound enhancement device that shields the sound
enhancement device from particulates in the air intake
passageway.
18. The method of claim 13, further comprising connecting an outlet
pipe to the assembly housing downstream of the sound enhancement
device, wherein the outlet pipe defines the sound passageway.
19. The method of claim 12, wherein the air intake passageway is
defined by a plenum downstream of the throttle body and one or more
intake runners extending from the plenum to one or more combustion
chambers of the engine.
Description
FIELD
The present disclosure relates to air intake systems for internal
combustion engines associated with outboard motor propulsion
systems.
BACKGROUND
U.S. Pat. No. 4,846,300, hereby incorporated by reference,
discloses a marine engine with a multi-section injection-molded
thermoplastic air box directing air to the fuel system's air intake
throat and silencing engine noise emitted back through the throat.
The air box has a cover section and a base section mounted to each
other solely by a seal along a peripheral seam around the entire
perimeter thereof, to prevent fuel leaks. The housing sections are
preassembled to each other prior to mounting to the air intake
throat. A removeable plug in the cover section allows access
through the cover section to bolts mounting the base section to the
throat. Access is also enabled to a fuel adjustment screw to enable
adjustment, with the air box fully assembled and mounted in place
on the throat, to enable adjustment under actual operating
conditions. Air guide passages and an air plenum chamber are all
molded in place.
U.S. Pat. No. 5,083,538, hereby incorporated by reference,
discloses an air intake system for an internal combustion engine
associated with the power head of an outboard marine propulsion
system. The engine includes a vertical crank shaft and a flywheel
mounted to the crank shaft above the engine block. An air manifold
is mounted to the forward side of the engine, and includes an air
inlet for receiving intake air. The air intake system includes an
air flow path or duct defined by a series of walls, a rearwardly
facing air intake opening, and a discharge opening for supplying
intake air to the air manifold inlet. The engine is enclosed within
a cowl assembly, and the air intake opening is located toward the
upper end of the cowl assembly interior. The walls defining the air
flow duct are formed integrally with a flywheel cover for
facilitating assembly of the air flow duct to the engine. The air
flow duct minimizes ingestion of water into the engine and reduces
engine noise in the boat.
U.S. Pat. No. 9,359,981, hereby incorporated by reference,
discloses an outboard motor including a system for enhancement of a
first subset of sounds having a desired frequency, and a method for
modifying sounds produced by an air intake system for an internal
combustion engine powering the outboard motor. The method includes
collecting sounds emitted in an area proximate a throttle body of
the engine. A first subset of the collected sounds, which have
frequencies within desired frequency range, is then amplified. The
amplified first subset of sounds is then transmitted to an area
outside a cowl covering the engine.
Unpublished U.S. patent application Ser. No. 15/091,007, filed Apr.
5, 2016, and hereby incorporated by reference, discloses an
outboard motor including an internal combustion engine and a cowl
covering the engine. An air vent allows intake air into the cowl,
an air intake duct routes the intake air from the air vent to the
engine, and a throttle body meters flow of the intake air from the
air intake duct into the engine. A sound enhancement device is
located proximate the throttle body. A sound duct is provided, and
has an inlet end located proximate the sound enhancement device and
an outlet end located proximate an outer surface of the cowl. The
sound enhancement device is tuned to amplify a first subset of
sounds having a desired frequency that are emitted from the
throttle body, and the sound duct transmits the amplified sounds to
an area outside the cowl. A method for modifying sounds produced by
an air intake system of an outboard motor is also provided.
SUMMARY
This Summary is provided to introduce a selection of concepts that
are further described below in the Detailed Description. This
Summary is not intended to identify key or essential features of
the claimed subject matter, nor is it intended to be used as an aid
in limiting the scope of the claimed subject matter.
According to one example of the present disclosure, an outboard
motor includes an internal combustion engine powering the outboard
motor and a cowl covering the engine and having a vent allowing air
under the cowl. A throttle body meters flow of the air into the
engine and an intake structure downstream of the throttle body
delivers the metered airflow to one or more combustion chambers in
a cylinder block of the engine. A sound enhancement assembly
including an assembly housing is in acoustic communication with the
intake structure and collects sounds emitted by the engine. The
sound enhancement assembly is configured to amplify a subset of the
collected sounds that have frequencies within a desired frequency
range.
Another example of the present disclosure includes a method for
modifying sounds produced by an air intake system of an internal
combustion engine powering an outboard motor. The method includes
positioning a sound enhancement assembly including an assembly
housing in acoustic communication with an air intake passageway
located downstream of a throttle body of the engine. The method
also includes tuning a sound enhancement device of the sound
enhancement assembly so that the sound enhancement device amplifies
a subset of sounds emitted by the engine that have frequencies
within a desired frequency range. The amplified subset of sounds is
transmitted as sound pressure pulses through a sound passageway of
the sound enhancement assembly to an area outside a cowl covering
the engine. Fluid communication between the air intake passageway
and the sound passageway is prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure is described with reference to the following
Figures. The same numbers are used throughout the Figures to
reference like features and like components.
FIG. 1 illustrates one example of a prior art outboard motor air
intake system.
FIG. 2 illustrates one example of an outboard motor according to
the present disclosure.
FIG. 3 illustrates one example of an air intake assembly and sound
enhancement assembly according to the present disclosure.
FIG. 4 illustrates portions of the assemblies described with
respect to FIG. 3.
FIG. 5 illustrates an assembled cross-sectional view of a sound
enhancement assembly according to the present disclosure.
FIG. 6 illustrates an exploded view of the sound enhancement
assembly of the present disclosure.
FIG. 7 illustrates one method for enhancing sounds produced by an
engine according to the present disclosure.
DETAILED DESCRIPTION
In the present description, certain terms have been used for
brevity, clarity and understanding. No unnecessary limitations are
to be inferred therefrom beyond the requirement of the prior art
because such terms are used for descriptive purposes only and are
intended to be broadly construed.
FIG. 1 is a simplified schematic illustrating a prior art outboard
motor 110 including a cowl 112 covering an internal combustion
engine 114. As is known, the engine 114 powers a propeller of the
outboard motor 110, via a series of connections and gears that
couple a crankshaft of the engine 114 to a propeller shaft. A
throttle valve located in a throttle body 116 meters intake of air
into the engine's combustion chambers 120, where the air is mixed
with fuel and ignited in order to drive the engine's pistons, which
movement causes the crankshaft to rotate. Air is provided to the
interior of the cowl 112 through an air vent 118, which is shown as
a simple hole extending through the cowl 112. However, it should be
understood that the air vent 118 can have a flap, shield, or
passage labyrinth provided over or around it in order to prevent
rain or water from entering the cowl 112.
In the system shown in FIG. 1, air enters through the air vent 118
and, as shown by the arrows labeled "A," flows through the open
under-cowl environment 122 toward the throttle body 116, where it
then flows past the throttle valve contained therein and into the
combustion chambers 120 of the engine 114. The throttle valve can
be either electronically or manually actuated. Sound produced by
the engine 114, including sound produced by the air intake system
(for example due to flow of air past the throttle valve in the
throttle body 116 or flow of air from an intake manifold into
intake passages leading into combustion chambers 120) leaves the
cowl 112 through the same vent 118, as shown by the arrow labeled
"S." Mechanical noise from the engine 114 is also transmitted out
of this vent 118, which is often located on the aft end or the side
of the cowl 112 in order to transmit the noise away from the
operator of the marine vessel to which the outboard motor 110 is
coupled. In certain outboard motors, the air intake system is
provided with a silencer that attenuates the noise produced by the
air intake system, such as described in U.S. Pat. Nos. 4,846,300
and 5,083,538, incorporated herein above. Other components, such as
an intake duct that acts as a resonator, may be attached to the
vent 118 and/or throttle body 116. The design of such a resonator
is typically optimized to balance tradeoffs between performance of
the engine 114, packaging of the engine 114 and its components
within the cowl 112, and noise vibration and harshness (NVH)
characteristics.
Product noise requirements and/or expectations of a given outboard
motor can vary greatly depending on the application. For example,
performance boaters may desire a louder and/or more powerful sound
quality than recreational boaters. However, expectations for sound
quality and refinement are universal, and dictated in some
geographical areas by law, regardless of the noise level
expectations of the customer. The system and method of the present
disclosure, described below with respect to FIGS. 2-7, enhance the
powerful, desirable sound characteristics of an outboard motor
without sacrificing the requirements and/or expectations for
refinement of unpleasant sound.
The outboard motor 10 of the present disclosure, shown in FIG. 2,
has the same components as that of the outboard motor 110 of FIG.
1, but also includes a sound enhancement assembly 32, as will be
described. The outboard motor 10 comprises an internal combustion
engine 14 powering the outboard motor 10. A cowl having an upper
portion 12 and a lower portion 13 covers the engine 14 and has a
vent 18 that allows air under the cowl 12, 13. A throttle body 16
meters flow of air into the engine 14. An intake structure 24 is
located downstream of the throttle body 16. The intake structure 24
can be or include any one or more of the following: an intake
plenum, an intake manifold, intake runners, a surge tank, or any
other combination of pipes and/or chambers. The intake structure 24
delivers the metered air flow from the throttle body 16 to one or
more combustion chambers 20 in a cylinder block 26 of the engine
14. For example, the intake structure 24 can be in fluid
communication with intake passages 28 extending through cylinder
head 30 of the engine 14. Many such arrangements for the engine 14
are well known in the art and will therefore not be described
further herein. The engine 14 could be any type/configuration of
engine, including but not limited to an in-line engine or a V-type
engine, and including any number of cylinders known to those having
ordinary skill in the art.
A sound enhancement assembly 32 is provided in the outboard motor
10. The sound enhancement assembly 32 is in acoustic communication
with the intake structure 24 and collects sounds emitted by the
engine 14, for example sounds emitted by air passing through the
throttle body 16, through the intake passages 28, into the
combustion chambers 20, etc. The sound enhancement assembly 32 is
configured to amplify a subset of the collected sounds that have
frequencies within a desired frequency range. As will be described
further herein below, the sound enhancement assembly 32 includes an
inlet pipe 34 coupled to or integral with the intake structure 24
that collects the sounds emitted by the engine 14. The sound
enhancement assembly 32 also includes an outlet pipe 36 that
transmits the amplified subset of the collected sounds to an area
outside the cowl 12, 13. A specific example, which is not limiting
on the present disclosure, will be described below.
Turning to FIG. 3, a side view of an air intake system for an
internal combustion engine equipped with one example of a sound
enhancement assembly 32 will be described. In this example, as
opposed to the examples described with respect to FIGS. 1 and 2,
the air intake system includes an air intake plenum or silencer, as
shown at 38. An inlet end 40 of the silencer 38 can be directly
connected to the vent 18 in the upper portion 12 of the cowl, or
can be located proximate the vent 18. Air enters the inlet end 40
of the silencer 38 as shown by the arrow labeled "A" and travels
through the silencer 38 into the throttle body 16. Air then
continues into the intake structure 24 from its upper end 50, to
which the throttle body 16 is coupled. In this example, the intake
structure 24 includes a plenum 42 (e.g. intake manifold) and four
intake runners 44a-44d connected to the plenum 42. After air enters
the plenum 42, it travels along each of the intake runners 44a-44d
to the cylinder head 30 (FIG. 2) and into, in this instance, four
combustion chambers 20. The plenum 42 may be coupled to the
cylinder block 26, a crank case cover, or another part of the
engine 14. Here, the sound enhancement assembly 32 includes an
assembly housing 47 that is coupled to a lower end 48 of the plenum
42 and is in acoustic communication with the intake structure 24.
However, the sound enhancement assembly 32 could be connected to
the intake structure 24, including but not limited to the plenum 42
and runners 44a-44d, anywhere upstream of the cylinder head 30 of
the engine 14. For example, the sound enhancement assembly 32 could
be coupled to the runner 44d. As shown, sound collected from the
engine 14 exits the sound enhancement assembly 32 as indicated by
the arrow labeled "S."
FIG. 4 illustrates a perspective view of the plenum 42 and the
runners 44a-44d. The separate and distinct passageways for both air
(labeled by the arrows A) and sound (labeled by the arrow S) are
shown. The sound enhancement assembly 32 is also shown at a
different angle, and includes the outlet pipe 36 and assembly
housing 47. Referring to both FIGS. 3 and 4, the assembly housing
47 comprises a first mounting flange 51 (intake side) that is
integral with the intake structure 24 and a second mounting flange
55 (outlet side) that is integral with an upstream end of the
outlet pipe 36. More specifically, an elbow piece 52 serves as the
upstream end for the outlet pipe 36 and comprises the integral
flange 55 that connects the outlet pipe 36 to the first mounting
flange 51 at the lower end 48 of the intake structure 24. The first
and second mounting flanges 51, 55 are connected to one another in
an airtight manner, as will be described herein below.
Now turning to FIGS. 5 and 6, the sound enhancement assembly 32
will be described in further detail. Both FIGS. 5 and 6 show the
lower end 48 of the plenum 42. The lower end 48 of the plenum 42 is
fashioned into the first mounting flange 51, which has a
cylindrical inner opening or aperture 35. In an example in which
the assembly housing connection to the sound enhancement assembly
32 is located at a different portion of the air intake assembly, or
on a different type of air intake structure, the first mounting
flange 51 might take other shapes, sizes, and/or forms than that
shown herein. An inlet pipe 34 coupled to the intake structure 24
collects sounds emitted by the engine and directs the sounds into
the assembly housing 47. Here, the inlet pipe 34 is made of two
separate parts, 64 and 60, which will be described further herein
below. The length and diameter of the inlet pipe 34 can be adjusted
to provide a desired sound level and frequency response. The
attachment location of the inlet pipe 34 and assembly housing 47
can be at any point along the intake path prior to the cylinder
head 30, as mentioned, and can be selected based on a variety of
factors, including complimentary frequency content of the sound
intake present at the attachment location, level of the intake
sound at the attachment location, packaging feasibility, airflow
disruption, etc. The assembly housing 47 provides a seat for the
remainder of the sound enhancement assembly 32 and should not allow
intake air to escape from between the intake structure 24 and the
sound enhancement assembly 32. For this and other purposes, the
sound enhancement assembly 32 may include a sound enhancement
device 54 (such as the flexible membrane shown herein) located
within the assembly housing 47, which provides a fluid-tight seal
between the sound enhancement assembly 32 and the air intake
structure 24.
The sound enhancement device 54 acts as a passive speaker that is
tuned to amplify a subset of sounds that have been collected from
the area where the sound enhancement assembly 32 is coupled to the
air intake structure 24. The sound enhancement device 54 adjusts
the spectral frequency (sound amplitude vs. frequency) of the
subset of sounds without the use of active components such as, for
example, electronic amplifiers. Because the sound enhancement
assembly 32 is passive, it relies on acoustic excitation of the
sound enhancement device 54 by sounds radiating from the air intake
structure 24 to provide amplification. This subset of sounds can be
defined in any way desired by the manufacturer/installer/operator.
For example, the subset of sounds may be sounds that have
frequencies within a desired frequency range, such as those that
produce what might be considered a pleasant "rumble" that conveys
the power of the engine 14 to the operator of the vessel. The sound
enhancement device 54 can be tuned to amplify this pleasant rumble
such that the operator can hear it better.
In one example, the sound enhancement device 54 extends generally
transversely across the aperture 35 (see FIG. 6) in a chamber
located between the inlet pipe 34 and the outlet pipe 36, as will
be described further herein below. The sound enhancement device 54
can have any sort of shape that will fill the cross-sectional shape
of the aperture 35, and its outer edges can be sealed along an
inner perimeter of the aperture 35 so as to isolate the remainder
of the sound enhancement assembly 32 downstream of the sound
enhancement device 54 from air flow in the interior of the air
intake passageway. Thus, the sound enhancement assembly 32 is not a
functional part of the air induction or exhaust system and does not
supply air to or remove air from the engine 14. In general, the
sound enhancement device 54 comprises some sort of
spring/mass/damper system. The sound enhancement device 54 could be
a flexible membrane, spring and disk, tuned plate, etc. For
example, the sound enhancement device 54 can be a tuned element
made of plastic or of a thin metal sheet attached to a spring that
can be tuned to achieve desired frequency characteristics. The
sound enhancement device 54 may take other forms, such as a
trumpet. In the example where the sound enhancement device 54 is a
membrane, the membrane may be made out of any sort of flexible or
elastomeric substance, and in one example is a disc made out of
rubber. A stiffness of the membrane can be tuned in order to
provide a desired amount of amplification of the subset of sounds
(the desirable sounds). The stiffness of the membrane can be varied
by stretching the membrane tighter or allowing the membrane to be
looser as it spans the aperture 35. Another way in which the
acoustic flexure properties of the membrane may be tuned or
adjusted is by varying the thickness (and therefore mass and
stiffness) of the membrane. Additionally, the composition of the
membrane itself and/or products that are applied to the membrane
can cause it to exhibit different characteristics upon application
of sound waves.
The sound enhancement assembly 32 also includes the above-noted
outlet pipe 36. The outlet pipe 36 has an upstream end, here
designed as the elbow piece 52 having the second mounting flange
55, which is coupled to the first mounting flange 51 downstream of
the sound enhancement device 54. The outlet pipe 36 also includes a
downstream pipe 53 coupled to the elbow piece 52 that transmits the
amplified subset of the collected sounds to an area outside of the
cowl 12, 13. The downstream end of the outlet pipe 36 is located
proximate an outer surface of the upper or lower portions of the
cowl 12, 13 (FIG. 2), so as to deliver the amplified subset of
collected sounds to the area outside of the cowl 12, 13. In the
example shown in FIG. 2, the downstream end of the outlet pipe 36
ends just outside of the cowl 12, 13, but it could be provided to
extend further through the cowl 12, 13 or to end just inside the
cowl. In one example, the downstream end of the outlet pipe 36 is
coupled to the lower portion 13 of the cowl (i.e. the chaps), which
is not required to be removed for servicing the engine 14.
(Generally, only the upper portion 12 is removed during routine
engine servicing.) Further, in the example shown in FIG. 2, the
downstream end of the outlet pipe 36 is positioned at a front side
of the outboard motor 10. In contrast, the air vent 18 is
positioned at the back side of the outboard motor 10. As mentioned
above, this allows unpleasant mechanical or air intake noises to
exit the cowl 12, 13 remote from the operator. The amplified
pleasant sounds exit the cowl 12, 13 closer to the operator. The
subset of sounds (shown by the arrow labeled "S1"), which have been
collected and amplified by their passage through the sound
enhancement assembly 32, are directed toward the operator of the
outboard motor, as they are emitted from the front side of the
outboard motor 10. Meanwhile, the sounds "S2" that are not in the
subset "S1" (i.e., sounds that do not have the desired frequency)
are emitted via the vent 18, which, because it is located on the
back side of the outboard motor 10, directs the undesired sounds
away from the operator. Thus, the operator can better hear the
amplified, desirable sounds than he or she can hear the
non-amplified remainder of the sounds.
Returning to FIGS. 5 and 6, the sound enhancement assembly 32
further includes a tensioner 60 that maintains a given tension of
the sound enhancement device 54. An inner circumference of a lip 61
that extends down on the bottom of the tensioner 60 acts as the
lower half of the inlet pipe 34. The height of the lip 61 of the
tensioner 60 stretches the sound enhancement device 54 to a desired
stiffness. The final tension of the sound enhancement device 54 is
set by the clamp load of the assembly housing 47 compressing the
outer (rigid) ring of the sound enhancement device 54 into its
final position, thereby stretching the sound enhancement device 54
over the lip 61 on the tensioner 60. Here, the tensioner 60 has a
central spine molded as the inner diameter of the part that acts as
an integral travel guard 63, such that the assembly housing 47
includes at least one travel guard 63, 62 on at least one of an
upstream side 56 and a downstream side 58 of the sound enhancement
device 54. The at least one travel guard 63, 62 prevents the sound
enhancement device 54 from distending by more than a predetermined
distance in response to a pressure pulse. For example, the upstream
travel guard 63 comprises a suspended central spine that prevents
against over travel of the sound enhancement device 54 in case of
an event creating a sudden intake manifold vacuum outside of
typical steady state operating conditions, such as for example
throttle chop. A downstream travel guard 62 is placed between the
sound enhancement device 54 and the elbow piece 52 of the outlet
pipe 36 to prevent over travel in case of an event creating a
sudden intake manifold increase in pressure outside of typical
steady-state operating conditions, such as for example
backfire.
The spacing of each travel guard 63, 62 is set to prevent contact
between the sound enhancement device 54 and the travel guards 63,
62 under typical steady-state operating conditions. This can be a
number of millimeters, such as for example 5 millimeters, but
depends on the desired steady state movement of the sound
enhancement device 54 in response to sound pressure pulses in the
air intake system. Although the tensioner 60 and downstream travel
guard 62 are shown herein as comprising circular disks having
central circular spines and support arms that radiate from the
central circular spine to an outer edge of the disk, other shapes
and configurations for the tensioner 60 and downstream travel guard
62 could be provided. The support arms are spaced apart such that
sound pressure pulses in the plenum 42 can act on the sound
enhancement device 54 and amplified sound pressure pulses created
by the sound enhancement device 54 can travel unhindered to the
outlet pipe 36. The tensioner 60 and downstream travel guard 62 can
be made from a reinforced polymer or alternative materials.
Ideally, the materials of the tensioner/travel guard are not
elastic and do not vibrate in response to sound pressure pulses
within the system. Thus, both of the tensioner 60 and downstream
travel guard 62 are acoustically transparent and do not
significantly affect the sounds traveling through the sound
enhancement assembly 32.
The sound enhancement assembly 32 may also include an acoustically
transparent shield 64 including an upper domed roof 65 positioned
above a lower tubular portion 67 of the shield 64 that makes up a
portion of inlet pipe 34. The shield 64 is located upstream of the
sound enhancement device 54 and protects the sound enhancement
device 54 from particulates in the intake structure 24 (i.e.,
plenum 42). This prevents the sound enhancement device 54 from
accumulating unwanted substances, which is especially useful if the
sound enhancement assembly 32 is positioned vertically within the
intake structure 24. Here, the shield 64 comprises the
above-mentioned lower tubular portion 67 that sits atop the outer
flange and lip 61 of the tensioner 60 and fits into the inner
diameter of the first mounting flange 51. A number of
circumferentially-spaced columns 69 extend upwardly from the lower
tubular portion 67 and support the upper domed (or conical) roof 65
that extends into the plenum 42 and sheds any particulates that
settle on it. The columns 69 are spaced apart such that sound
pressure pulses in the plenum 42 can act on the sound enhancement
device 54. Of course, other constructions for the shield 64 are
within the scope of the present disclosure. The shield 64 could be
made of a reinforced polymer or other materials. Ideally, the
material of the shield 64 is not elastic, does not vibrate in
response to sound pressure pulses within the system, and thus does
not have a significant effect on the sounds emitted from the sound
enhancement assembly 32.
In this example, the tensioner 60 and the shield 64 each have a
cylindrical inner diameter that together form the inlet pipe 34.
Tensioner 60 has an inner diameter defined by lip 61 that defines
the lower half of the inlet pipe 34, and shield 64 has an inner
diameter defined by tubular portion 67 that defines the upper half
of the inlet pipe 34. The length of this inlet pipe 34 is dictated
by the sum of the heights of the openings in both the tensioner 60
and the shield 64, and the diameter of the inlet pipe 34 is
dictated by the inner diameter of these two parts. In this
embodiment, in order adjust the physical dimensions of the inlet
pipe 34 such as its length and diameter, these two components 60,
64 would require modification. This is potentially a desirable
tuning parameter for the sound enhancement assembly 32.
An O-ring 66 may be provided between the shield 64 and the
tensioner 60 in order to seal the tensioner 60 to the first
mounting flange 51. An optional tension adjustment ring 68 may be
provided between the tensioner 60 and the sound enhancement device
54. This tension adjustment ring 68 is a tuning component that can
be provided with different thicknesses in order to stretch the
sound enhancement device 54 to different tensions for alternative
tuning frequencies. The thickness of the tension adjustment ring 68
adjusts the effective height of the lip 61 on the primary tensioner
60, allowing for various tension settings for the sound enhancement
device 54. For example, a thinner tension adjustment ring 68 would
effectively create a longer lip 61 and thus cause the sound
enhancement device 54 to be stretched tighter across the aperture
35. See FIG. 5.
A seal 70 is provided between the downstream side 58 of the sound
enhancement device 54 and the outlet portion of the assembly
housing 47 (i.e., elbow piece 52). The seal 70 is preferably made
of a compressible material in order to provide an airtight seal
between the first mounting flange 51 and the second mounting flange
55 on the elbow piece 52. The seal 70 has an inner ring-shaped
circumference 73 that holds the outer circumference of the
downstream travel guard 62 therein. The seal 70 also has an outer
flange 75 for holding the seal 70 to the remainder of the sound
enhancement assembly 32. The elbow piece 52 and seal 70 are held to
the inlet portion of the assembly housing 47 (first mounting flange
51) by way of one or more fasteners, such as the bolts 72 shown
herein, that pass through holes in their respective flanges 55, 75
and into corresponding holes surrounding the aperture 35 in the
first mounting flange 51.
The downstream pipe 53 of the outlet pipe 36 can be friction fit
over the downstream end of the elbow piece 52. In another example,
the outlet pipe 36 is integrally formed from the second mounting
flange 55 that sits against the seal 70 and is bolted to the first
mounting flange 51 all the way to the downstream end that exits the
cowl 12, 13. In another example, the outlet pipe 36 includes a
separate or integral flanged piece that is other than an elbow
shape. The elbow piece 52 serves as the outlet portion of the sound
enhancement assembly housing 47. The outlet portion needs an
attachment connection for the outlet pipe, which in this example
happens to be a 90 degree elbow. This outlet pipe attachment could
instead be oriented at any angle, and its shape could be selected
in order to provide ease of routing to the desired outlet location
at the cowl. The inner diameter of the outlet pipe 36 is a tuning
parameter for the sound enhancement assembly 32, and this could be
adjusted to any diameter. Note that the outlet pipe 36 could also
be provided with twists, turns, and varying diameters before it
exits the cowl 12, 13. This can allow the outlet pipe 36 to snake
around other engine components, or can provide different
characteristics to the sound emitted from the outlet pipe 36.
For example, the outboard motor 10 shown in FIGS. 2-6 can also be
designed to attenuate a second subset of the sounds emitted from
the engine 14. This second subset of sounds may have frequencies
that are within an undesired frequency range. For example, these
may be sounds having a frequency that might be considered annoying
to the operator of the outboard motor 10. In order to attenuate the
second subset of sounds, the length and/or shape of outlet pipe 36
can be selected specifically to provide a desired amount of
attenuation. Alternatively or additionally, a stiffness of the
sound enhancement device 54 can be tuned to provide a desired
amount of attenuation of the second subset of sounds. Additionally
or alternatively, a sound attenuating device may be provided within
the outlet pipe 36 so as to provide a desired amount of attenuation
of the second subset of sounds. The sound attenuating device could
be a small fibrous pad, another type of padded material, foam
inserts, or a similar spongey-type material that is designed to
attenuate certain frequencies of sounds. Optionally, tube wall
compliance (elasticity) can be used to provide additional damping.
Therefore, the system provides enhancement of desirable engine
sound characteristics, while minimizing unwanted sounds that
radiate from cowl openings. By suppressing unwanted sounds and
highlighting desirable sounds, a more refined sound quality can be
obtained.
Now turning to FIG. 7, a method for modifying sounds produced by an
air intake system of an internal combustion engine 14 powering an
outboard motor 10 will be described. The method begins at start
700. Next, as shown at 702, the method includes positioning a sound
enhancement assembly 32 in acoustic communication with an air
intake passageway located downstream of a throttle body 16 of an
engine 14. In one example, the air intake passageway may be defined
by a plenum 42 (e.g., an air intake manifold) downstream of the
throttle body 16 and one or more intake runners 44a-44d extending
from the plenum 42 to one or more combustion chambers 20 of the
engine 14. As shown at 704, the method may further include tuning a
sound enhancement device of the sound enhancement assembly 32 so
that the sound enhancement device amplifies a subset of sounds
emitted by the engine 14 that have frequencies within a desired
frequency range. As described herein above, the sound enhancement
device 54 may comprise a flexible membrane. In the example where
sounds are collected by an inlet pipe 34 coupled to the air intake
passageway, the method may further include placing the sound
enhancement device 54 (membrane) in an assembly housing 47. The
method may further include placing the sound enhancement device 54
across an inner diameter of the assembly housing 47 and maintaining
a desired tension on the sound enhancement device 54 by contacting
it with a tensioner 60. Further tensioning adjustment may be
provided, for example, by way of a tension adjustment ring 68
fitted between the sound enhancement device 54 and the tensioner
60.
Further, the method may also include providing at least one travel
guard 63, 62 in the housing that prevents the sound enhancement
device 54 from distending by more than a predetermined distance in
response to a pressure pulse, such as that created by backfire or
throttle chop. The method may include providing a first travel
guard 63 (for example, integral with the tensioner 60) on an
upstream side 56 of the sound enhancement device 54 and a second
travel guard 62 on a downstream side 58 of the sound enhancement
device 54. The method may further comprise shielding the sound
enhancement device 54 from particulates in the intake passageway,
such as by way of shield 64, as described herein above with respect
to FIGS. 5 and 6.
Returning to FIG. 7, as shown at 706, the method may include
transmitting the amplified subset of sounds as sound pressure
pulses through a sound passageway of the sound enhancement assembly
32 to an area outside a cowl 12, 13 covering the engine 14. For
example, the method may include connecting an outlet pipe 36 to the
assembly housing 47 downstream of the sound enhancement device 54,
wherein the outlet pipe 36 defines the sound passageway. The method
may further include, as shown at 708, preventing fluid
communication between the air intake passageway and the sound
passageway. This portion of the method in effect occurs
simultaneously to the remainder of the portions of the method, as
fluid communication between the air intake passageway and the sound
passageway is prevented by provision of the sound enhancement
device 54 that extends across the inner diameter of the assembly
housing 47. The sound enhancement device 54 does not allow air to
pass through it. In other words, sound pressure pulses on an
upstream side 56 of the sound enhancement device 54 cause the sound
enhancement device 54 to vibrate and create amplified sound
pressure pulses on a downstream side 58 of the sound enhancement
device 54 in air that is not in communication with air on the
upstream side 56 of the sound enhancement device 54. This way,
intake air is not released to the atmosphere through the sound
passageway. The sound enhancement assembly 32 is therefore not a
part of the air intake flow path and does not provide air to the
combustion chambers 20 nor does it convey air away from the
combustion chambers 20 that should otherwise be provided for
combustion. The method concludes at 710.
Optionally, a sound throttle can be used to control the volume
contribution of the amplified sound coming from the sound
enhancement assembly 32. For example, see element 74 in FIG. 2. The
sound throttle 74 may be a butterfly valve located between the
attachment location of the sound enhancement assembly 32 to the air
intake structure 24, such as just upstream of the inlet pipe 34,
and can be of similar diameter to the inlet pipe 34. Alternatively,
the sound throttle 74 can be placed between the shield 64 and the
tensioner 60 or downstream of the sound enhancement device 54 at
any position along the outlet pipe 36. The sound throttle 74 can be
electronically controlled, with calibrated positions intended to
deliver a target level of sound based on engine load. The sound
throttle 74 can also be used to create a variety of intake sound
profiles which can be selected by the user (for example, race,
sport, quiet modes, etc.). Essentially, the sound throttle 74 works
as a volume knob rather than changes the character of the sound
produced by the sound enhancement assembly 32. For example, when
wide open throttle speed is requested by the operator, the sound
throttle 74 of the sound enhancement assembly 32 could be fully
open. The sound throttle 74 could be closed or partially open for
lighter load cases, such as when the engine 14 is operated at less
than wide open throttle speed.
The sound enhancement assembly 32 of the present disclosure has an
increased impact on the sound signature produced because the sound
source (i.e. the inlet pipe 34 and sound enhancement device 54) can
be located at a strategic point downstream of the throttle body 16.
Note that when a sound enhancement device is placed upstream of the
throttle body 16, pressure pulses from each combustion chamber 20
are more or less combined into a single noise source, meaning a
device upstream of the throttle body 16 acts more like a volume
knob for the intake sound that is already present. However, by
locating the sound device downstream of the throttle body 16, there
is a greater potential to locate, identify, and isolate noise
contributions from different portions of the engine's air intake
passageways. Additionally, attachment of the sound enhancement
assembly 32 at various points along the intake passageway can
create more packaging options, allowing the sound enhancement
assembly 32 to be used with more outboard motor package types.
In the above description, certain terms have been used for brevity,
clarity, and understanding. No unnecessary limitations are to be
inferred therefrom beyond the requirement of the prior art because
such terms are used for descriptive purposes and are intended to be
broadly construed. The different systems and method steps described
herein may be used alone or in combination with other systems and
methods. It is to be expected that various equivalents,
alternatives and modifications are possible within the scope of the
appended claims.
* * * * *
References